Proxmox Ceph HA on Five Dell OptiPlex Micro 3060s: USB or 2.5GbE NICs?

Yes, it will work, but you need realistic expectations. The theme that kept coming up is that micro "blade-style" systems and Ceph are a poor match in philosophy. Ceph prefers fat nodes with plenty of local disks and strong networking. These tiny OptiPlex nodes can run it, but they are not its natural habitat.

Performance is the main warning. Several people who tried nearly identical setups report that write-heavy workloads can become painfully slow. Even routine tasks like package updates inside a VM caused noticeable slowdowns across the whole cluster. It works, but under pressure it can feel like walking through mud.

Networking matters more than people expect. Thanks to VLAN tagging you do not strictly need two physical NICs, but on 1GbE Ceph replication traffic competes hard with VM traffic. Several experienced users recommend at least 10Gb networking for comfortable Ceph performance. Others got decent results with 2.5GbE through M.2 adapters in the WiFi slot, which is cleaner and more reliable than USB NICs. USB Ethernet can work, though stability and driver support vary.

Storage quality was another repeated caution. Consumer SSDs often struggle with Ceph's write patterns because of limited DRAM buffers and weak sustained write performance, and enterprise-grade SSDs make things far more consistent. Commonly suggested baselines are at least two OSDs per node and ideally four or more nodes.

So yes, you can build it, and it will form a real HA cluster. As a playground for learning Ceph it is fantastic. For performance-sensitive workloads, temper your expectations. This is a lab experiment, and nobody should mistake it for a production rocket ship.